Joplin is a free, open source note taking and to-do application. Joplin fails to take into account that "<" followed by a non letter character will not be considered html. As such it is possible to do an XSS by putting an "illegal" tag within a tag.
Severity
CVSS 3.1
9.6 critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
EPSS
0.8% chance of exploitation in the next 30 days; higher than 56% of CVEs (scores of 2026-10-31)